This application is for a competitive renewal and transformation of the HMO Cancer Research Network (CRN) into a research resource. The CRN, which has been continuously funded since 1999, provides infrastructure support to conduct cancer research in the setting of not-for-profit integrated health care delivery systems. The setting has advantages for conducting population sciences research that collectively result in a unique, unparalleled resource for conducting epidemiologic and health services research in cancer. These advantages include externally-funded research groups with investigators with expertise in conducting public-domain cancer research in these settings; defined populations with a combined membership of over 10 million individuals for whom health care is provided; clinical and administrative data systems that capture most aspects of care; development and implementation of common data models in the Virtual Data Warehouse (VDW) to facilitate collaborative and multi-institutional research; and access to clinicians and administrators to facilitate translation of research findings to practice. We plan to enhance the CRN in several areas, including: Establishing an Informatics Core focused on continual improvement of the VDW through implementation of distributed query tools to facilitate preparatory-to-research and collaborative research studies, and improvement of existing and implementation of new VDW domains of relevance to cancer research; identification and promotion of research in strategic areas for which the CRN is uniquely positioned (i.e., Prevention & Screening; Treatment & Outcomes; Biospecimens & Molecular Applications; Communications & Decision-Making; Health Care Quality & Cost; and Dissemination & Implementation); institutionalizing a CRN Scholars mentored career development program for junior investigators; continuation of a Developmental and Pilot Studies Program to support pilot studies and to enhance infrastructure; and implementation of an Outreach and External Collaborations Core to facilitate research collaborations. This continued infrastructure support will enable and facilitate researchers' continued access to large integrated delivery systems and motivate continued evolution as the nation's premier learning healthcare systems.